Sciencemadness Discussion Board

How to make a 1% aqueous solution?

qton - 4-12-2009 at 19:09

Hi, I've purchased the following powders so I can make solutions (e.g. 1% aqueous for Methylene Blue). Thought this would be a problem but Google hasn't turned up anything. Can anyone please direct me to a reference that describes how to do this?

Eosin Y, certified C.I. #45380
Methylene blue, certified C.I. #52015
Indian Ink / Nigrosin, w/s C.I. #50420
Basic fuchsin, certified C.I. #42510
Gentian violet C.I. # 42555
Safranin O, certified C.I. #50240
Neutral red, certified C.I. #50040

Thanks!

http://www.sciencemadness.org/talk/viewthread.php?tid=12837&...

psychokinetic - 4-12-2009 at 19:12

99g H2O : 1g powder?

Or do you require a specific molarity?

qton - 4-12-2009 at 19:39

Quote: Originally posted by psychokinetic  
99g H2O : 1g powder?

Or do you require a specific molarity?


Hey thanks, psychokinetic. I assumed it would be something to do with molarity, but it didn't occur to me it would be that simple. I've only ever seen microscope stains these described just as e.g. "Eosin 1% aqueous" though I did find a few that added "(w/v)" which I'm guessing is as you describe?


Sedit - 4-12-2009 at 21:46

He discribed w/w you want something else. besides that if you want w/v

qton - 4-12-2009 at 22:52

Thanks Sedit and psychokinetic. I realise now I should have been googling for w/v instead of aqueous:
Quote:

In biology, percentage solutions are often preferred to molar solutions. A 1% solution would have 1 g of solute dissolved in a final volume of 100 mL of solution. This would be labeled as a weight/volume [w/v] percentage solution.

http://en.wikipedia.org/wiki/Percentage_solution

devongrrl - 5-12-2009 at 04:41

on a similar subject can someone clarify for me which is more concentrated:

a 38% Nitric acid solution or a 5M solution ?

If my maths are correct, I *think* 38% equates to about 7M

Am I correct ?

entropy51 - 5-12-2009 at 12:00

qton, the usual method of preparing biological stains from those dyes is to dissolve the powder in a minimal amount of 95% ethanol and then dilute to the required volume with distilled H2O. For staining w/w and w/v are equally good.

psychokinetic - 5-12-2009 at 12:19

All good, glad that even though I wasn't answering quite what you wanted, you found what you needed :)

qton - 12-12-2009 at 18:55

Thanks everyone for your help!
Quote: Originally posted by entropy51  
qton, the usual method of preparing biological stains from those dyes is to dissolve the powder in a minimal amount of 95% ethanol and then dilute to the required volume with distilled H2O. For staining w/w and w/v are equally good.


And that's for that advice, entropy51. It's amazing how much of this stuff doesn't seem to be written down anywhere. Just out of interest why dissolve it in ethanol? I have some Methylated Spirits (95% ethanol, 5% methanol) which I guess would do the trick? (I was also going to try and use it for Gram's Stain.)

(BTW is it just me or is it weird that the only reason Methylated Spirits contains poison methanol is so the Govt can charge outrageous tax on alcohol without it?)

DJF90 - 13-12-2009 at 02:29

Yep, thats exactly what the methanol/other denaturants are for; to stop people drinking it, as it is essentially tax free alcohol (+ other goodies you dont want to be drinking). Entropy is right about dissolving the stain first in ethanol, but methylated spirits should do fine so long as they are not coloured... If they are (generally a blue/purple dye) then you're going to have to distill it.

entropy51 - 13-12-2009 at 09:11

Quote:
It's amazing how much of this stuff doesn't seem to be written down anywhere.
Well actually, it's amazing that you haven't found any of it.

Try a Google search using "bacteriology" together with "preparation of stains". Here's one that I found in just a minute or two. There are plenty more. I found out how to do gram stains in about 1960, without the internet or a computer of any kind. Do people still go to libraries?

qton - 14-12-2009 at 23:25

Quote: Originally posted by DJF90  
Yep, thats exactly what the methanol/other denaturants are for; to stop people drinking it, as it is essentially tax free alcohol (+ other goodies you dont want to be drinking).

But it seems so wrong... like I'm propping up an inefficient government not earning their tax honestly. :-)
Quote: Originally posted by DJF90  

Entropy is right about dissolving the stain first in ethanol, but methylated spirits should do fine so long as they are not coloured... If they are (generally a blue/purple dye) then you're going to have to distill it.


Thanks DJF90. The methylated spirits is clear. BTW what is the chemical reason for using a bit of alcohol first before the water?
Quote: Originally posted by entropy51  
Well actually, it's amazing that you haven't found any of it. Try a Google search using "bacteriology" together with "preparation of stains". Here's one that I found in just a minute or two. There are plenty more. I found out how to do gram stains in about 1960, without the internet or a computer of any kind. Do people still go to libraries?


Thanks for the pointer! Haven't done too well with Google, but found (like the "w/v" thing) once you get the right keywords the dam bursts open. Our municipal library system is usually pretty good, but for the Science books are either light and fluffy or "popular science" at best. The only microscopy book was one you might give a 12 year old, and it said nothing about stains. They did have "Microbiology Demystified" but the stupid thing doesn't have photos or even diagrams of the microorganisms!

The winning combination seems to be looking for textbook torrents, then buying the good ones on Abebooks which are absurdly cheap. Some of them are drowned in highlighter, but at $2 a pop I can live with it!

1960? Wow. I have a good excuse not to have been doing it then though. :-)

entropy51 - 15-12-2009 at 09:54

Quote:
Our municipal library system is usually pretty good, but for the Science books are either light and fluffy or "popular science" at best. The only microscopy book was one you might give a 12 year old, and it said nothing about stains. They did have "Microbiology Demystified" but the stupid thing doesn't have photos or even diagrams of the microorganisms!
The library in the small town where I grew up had no micro books at all. But a high school teacher still had his micro book from college and loaned it to me. There's plenty of stuff on the web and for micro even the ancient books have a lot to teach a beginner. You do know about gigapedia, don't you?

DJF90 - 15-12-2009 at 10:50

The reason for dissolving first in alcohol is to aid solution; however the small % ethanol may play some role with the specimens you are attempting to stain (perhaps allowing them to stain easier?) but this is not something I can claim to be an expert in.

psychokinetic - 15-12-2009 at 11:57

Quote: Originally posted by entropy51  
Do people still go to libraries?


I'd live in my university library if I could :P

But then, I'd get no chemistry done!

entropy51 - 15-12-2009 at 14:53

Quote:
I'd live in my university library if I could. But then, I'd get no chemistry done!
With online access to some good journals, you can do the same thing without leaving home!

psychokinetic - 15-12-2009 at 21:12

Indeed entropy - my university gives me free access to many, many online journals. You name it, I can probably access it.

Hey Devon - seems you got lost in the conversation! It's about as 6.03M/L

- 38g divided by 63.012g/mol = 0.603g/100ml
.................................times 10 = 6.03g/L

Feel free to tell me I'm wrong and inform me of the correct way. This is what I gathered from my chemistry textbook (Which eals with every calculation BUT %-M :P)